With 1280x1024 secondary monitor should new primary monitor be 16:9 or 16:10 using Ultramon

I've recently had my main monitor die and am ready to upgrade to a larger monitor. My secondary monitor is a Dell 1280 x 1024 older monitor. I'm ready to go to the newer, wider resolution modern monitor but I'm a bit concerned about how the two will match up using Ultramon (dual monitor software). I like to stretch my desktop across both monitors and use one background image that also spans across both monitors. Am I correct in assuming that a 16:9 (1920x1080) will work better than a 16:10 (1920x1200) next to the 1280x1024 since the vertical resolutions are closer? Are there any issues that I'm going to face in trying to do this? I'm sure many of you simply buy two 16:9 or 16:10 monitors at the same time...but I can't spend that much right now.

The two monitors I'm considering are the Dell UltraSharp U2412HM and the Dell UltraSharp U2312HM. I'm mainly office, and internet use with about 1/3 gaming (BF4).